We can compute a limit on the emission height for the pulsars in the RVM class in the following (geometric) way. If we assume that the beams are filled and that \(\alpha =90\)  for all pulsars, an upper limit on the emission height is given by Equations REF  and REF . The resultant histogram of heights computed in this way is shown in Figure REF . From this figure we see that 35% of the pulsars have \(h_{\rm max} < 300\)  km and 77% have \(h_{\rm max} < 1000\)  km. This provides strong evidence that the radio emission from pulsars arises from low altitude, and does not depend greatly on the spin period [1]}, [2]}. In addition we also note that pulsars with apparent \(h_{\rm max} > 1000\)  km have predominantly low values of \(\dot{E}\) . Given that \(\alpha \)  evolves with time, these pulsars likely have \(\alpha \)  significantly less than 90 and as a result lower emission heights than \(h_{\rm max}\) .
